Maven restructure to support multiple versions

- Common module for interfaces for versioning
- Core module for the main code
- Version modes for specific versions
- Note: The plugin version in the plugin.yml is not correct as of yet

Imports optimized

Updated for 1.20.4

- Added config option to allow arenas to still load even when materials fail to load

Merge remote-tracking branch 'origin/master'

Merge branch 'fix-#6'

I forgot to update the pom

0.7.2

In this commit:
- Added warnings for loading arenas made in newer versions of minecraft
- Added handling for when a material can't be identified at all (made in newer minecraft versions)
- Added BeaconWrapper to support beacon NBT
- Added support for glowing signs
- Fixed 1.16+ sign support not working

0.7.1

- Fixed arenas resetting from the point they were canceled at
- Fixed the reload command not reloading the reset speed config options
- Optimized arena loading to load in parallel, making load times much faster
- Added `-silent` option to the reset command to reset something without constant updates (useful when executing the command as the console)
- Added more documentation

Finished 0.7

- Rewrote how NBT is stored in arena files
    - It is now much more compact when multiple blocks that have the same NBT. E.g. placing 10 banners of the same kind will now only store 1 version of the NBT and not 10
- Added TeleportCommandSuggestion to the config
- Made SkullWrapper write less data to file (now only some is in JSON compared to the entire thing)
- Added reload command
- Made the reset command able to edit an existing reset's speed

Added progressive reset messages

- Added progressive reset messages sent to users every so often to update them how the reset is doing
- Added more options to the config for how often it is
- Completed tab completion of commands